Alpha Checked against MI

Alpha E-Tec Plus combi (28, 33, 38)

Combi, natural gas (LPG by conversion kit)

Combustion figures

Figure	Natural gas (G20)	LPG (G31)
CO₂ at high rate More infoHide info CO₂ at maximum DHW output (99% in chimney sweep mode), which is the maximum the MI checks and sets (MI 6.6, 6.12). Check with the case fitted; after any gas valve adjustment wait about 30 seconds for the boiler to stabilise. The MI also gives CO₂ at maximum CH output with no tolerance: NG 28: 9.7%, 33: 9.5%, 38: 9.2%; LPG 28: 11.4%, 33: 11.2%, 38: 10.85%. MI 6.6 says CO₂ testing at maximum CH output (80–90%) is not required. MI 6.6 refers to Section 2.1 for the tolerance, but 2.1 is Electrical supply; MI 6.12 points to Section 3.1.	E-Tec Plus 28 9.7% (+0.5/−0.2%) E-Tec Plus 33 9.5% (±0.2%) E-Tec Plus 38 9.2% (+0.4/−0.2%)	E-Tec Plus 28 11.4% (+0.1/−0.3) E-Tec Plus 33 11.2% (+0.2/−0.4) E-Tec Plus 38 10.9% (+0.4/−0.2%)
CO₂ at low rate More infoHide info At minimum output (0% in chimney sweep mode), case fitted (MI 6.12).	E-Tec Plus 28 8.8% (+0.2/−0.3%) E-Tec Plus 33 8.6% (+0.2/−0.3%) E-Tec Plus 38 8.5% (+0.1/−0.3%)	E-Tec Plus 28 10.6% (+0.3/−0.1) E-Tec Plus 33 10.0% (+0.4/−0.2) E-Tec Plus 38 9.9% (+0.4/−0.2%)
Maximum CO More infoHide info The LPG table (MI 3.2) gives no CO figure and says other technical data is the same as NG data.	450 ppm	450 ppm
CO/CO₂ ratio More infoHide info Given as Maximum CO/CO₂ ratio in MI 3.1. MI 7 says the ratio should be less than 0.004. The LPG table says other technical data is the same as NG data.	0.004	0.004
O₂	Not given in MI	Not given in MI
Working inlet pressure More infoHide info Measurement point not stated in MI. Given as Gas supply pressure in the technical data (MI 3.1, 3.2), with no range.	20 mbar	37 mbar
Gas rate at maximum	E-Tec Plus 28 3.05 m³/h E-Tec Plus 33 3.45 m³/h E-Tec Plus 38 4.13 m³/h	E-Tec Plus 28 2.24 kg/h (0.62 g/s) E-Tec Plus 33 2.53 kg/h (0.70 g/s) E-Tec Plus 38 3.03 kg/h (0.84 g/s)

From Part No. 1.043044 rev. ST.004614/001 (0220/D409)

Enter service mode for high and low rate

High rate

With no heating or hot water demand, hold RESET for 8 seconds. The parasol and snowman symbols flash together.
Press the hot water ▲ button (tap symbol) to step up to maximum, 99%. The levels are 0%, 80–90% and 99%.
If a Climatic controller is fitted it shows ERR>07. That’s not a fault.

Low rate

Press the hot water ▼ button (tap symbol) to step down to minimum, 0%.

Ending the test

Turn the boiler off to come out (hold the Off/Stand-by/Summer/Winter button for 8 seconds). It also ends by itself after 15 minutes.

Models and GC numbers

Model	GC number	Gas
Alpha E-Tec Plus 28	47-532-77	NG
Alpha E-Tec Plus 33	47-532-78	NG
Alpha E-Tec Plus 38	47-532-79	NG

Source: Alpha E-Tec Plus 28, 33 and 38 Installation and Servicing Instructions, Part No. 1.043044 rev. ST.004614/001 (0220/D409).

Sections: 3.1 Technical performance data - natural gas; 3.2 Technical performance data - LPG; 6.6 Checking the combustion - chimney sweep mode; 6.11 Converting the boiler to operate on LPG; 6.12 CO2 set up procedure; 7 Routine servicing (combustion check).

Spotted something wrong? Tell us.

Check these figures against the MI for the appliance in front of you, matched by GC number and manual date. Combustion work needs a calibrated analyser and a Gas Safe registered engineer.